Karla Washington at her office on the University of Nevada campus in Las Vegas. Ms. Washington, an undergraduate student, earns less than $11,000 a year from her job, which must cover food, rent, health, and child care.

There has been a "significant decline" in economic well-being for low-income children and families over the past decade as the official child poverty rate grew by 18 percent and poverty levels for families with children increased in 38 states, according to a new study.

Economic and housing difficulties are the main culprits, reports the Annie E. Casey Foundation, a private charitable organization that focuses on disadvantaged children.

“The recent recession has wiped out many of the economic gains for children that occurred in the late 1990s,” said Laura Speer, associate director for policy reform and data at the Casey Foundation, as the report was released Wednesday. “Nearly 8 million children lived with at least one parent who was actively seeking employment but was unemployed in 2010. This is double the number in 2007, just three years earlier.”

“The news about the number of children who were affected by foreclosure in the United States is also very troubling because these economic challenges greatly hinder the well-being of families and the nation,” said Ms. Speer.

In the United States as a whole, nearly 15 million children (20 percent) live in poverty. A broader definition of economic straits – $43,512 a year, or twice the federal poverty line for a family of four, “a minimum needed for most families to make ends meet,” as Speer puts it – includes 31 million children, or 42 percent of the total.

According to the National Center for Children in Poverty at Columbia University, low-income rates for young children are higher than those for older children – 43 percent of children under age six live in low-income families, compared with 37 percent of children over age six.

With record high unemployment (12.1 percent) and home foreclosure rates, Nevada saw a 38 percent increase in child poverty over the past decade. Foreclosures have affected the lives of 13 percent of the children in Nevada (the highest such rate in the US), and about one-third of all Nevada children were in families where neither parent had full-time work in 2009.

"My biggest fear is not providing my daughter with everything that she needs to be a balanced child, to be independent, to be safe, to feel like she is of value," Karla Washington, a single mother earning less than $11,000 a year at her part-time job while attending the University of Nevada, Las Vegas, told the Associated Press.

The impact of the problems revealed in the Casey Foundation report – which is based on data from the Mortgage Bankers Association, National Delinquency Survey, the US Census Bureau, and other government and private sources – could go well beyond the immediate harm to a large percentage of today’s children.

“People who grew up in a financially secure situation find it easier to succeed in life, they are more likely to graduate from high school, more likely to graduate from college, and these are things that will lead to greater success in life,” Stephen Brown, director of the Center for Business and Economic Research at the University of Nevada, Las Vegas, told the AP. “What we are looking at is a cohort of kids who as they become adults may be less able to contribute to the growth of the economy. It could go on for multiple generations.”

There was some good news in the Casey Foundation report.

The infant mortality rate, child death rate, teen death rate, teen birth rate, and the percent of teens not in school and not high school graduates have improved since 2000. At the same time the percent of babies born low-birthweight, the child poverty rate, and the percent of children living in single-parent families have worsened.